The invention relates to a closure electrifier with a low mass transformer.
Electrical closures are adapted to protect spaces, and particularly fields, against intrusion or the escape of an animal for example. These closures comprise essentially a conductive element, such as a wire, cable or strip, delimiting the space to be protected, and an electrifier adapted to send through the conductive element, high voltage pulses of controlled energy. To ensure insulation between the conductive element of the closure and the electrical supply source of the electrifier, this latter comprises a transformer which also ensures the increase of voltage of the output pulses to the required level.
The state of the art is shown in FIG. 1, in which a condenser 1 is charged with a voltage Vc, and periodically discharged into the primary 4 of a transformer (4-5-6) under the control of a thyristor 2. The impulse applied to the conductive element of the closure is available between the terminals 23 and 24 of the secondary 5 of the transformer (4-5-6), and has an amplitude and a duration. The amplitude corresponds to the voltage at the output terminals 23, 24 of the transformer. The electrical energy of the pulse is proportional on the one hand to its amplitude, on the other hand to its duration.
The electrical energy stored in the condenser 1 is transmitted to the conductive element of the closure by means of the transformer (4-5-6). This energy transmission takes place with a satisfactory output so long as the magnetic circuit 6 is not saturated. Beyond saturation, the losses in the magnetic circuit 6 increase very rapidly. The current in the primary 4 of the transformer reaches high values, which gives rise to large losses from the Joule effect. Any increase of the energy stored in the condenser 1 thus corresponds only to a marginal increase of the energy transmitted to the conductive element of the closure.
If the pulse energy applied to the conductive element of the closure must be substantially increased, it is then necessary to use an unsaturated magnetic circuit, which is to say a magnetic circuit of a higher cross-section and hence of larger dimensions and greater mass, and higher cost.
An object of the present invention is to provide a closure electrifier which permits transmitting high energy pulses with a low mass transformer.
The invention has for its object a closure electrifier with a transformer having a low mass magnetic circuit, comprising a transformer with insulation of the conductive element of the closure connected to the secondary of the transformer, a condenser for storing electrical energy and a thyristor adapted to be rendered conductive by a control signal applied to its trigger, to ensure the discharge of the surge condenser through the primary of the transformer and the delivery of a pulse to the secondary, characterized in that it comprises
several storage condensers mounted in parallel,
several thyristors each mounted in parallel on one condenser to ensure the individual discharge of each condenser without modification of the condition of the other condensers, and in that
the discharge of the condensers is controlled sequentially so as to deliver to the secondary of the transformer a complex pulse comprised by a series of elemental pulses, each elemental pulse corresponding to the individual discharge of one condenser, this individual discharge being ordered only when the magnetic circuit has returned to its initial condition.
According to other characteristics:
the primary of the transformer is mounted between the point common to the storage condensers and the point common to the thyristors;
each one of the storage condensers is mounted in series with a diode, said diodes having a common point;
the common point of the diodes is the cathode;
the common point of the diodes is the anode;
each circuit branch comprising a condenser and a diode in series is mounted between the point common to the condensers and the point common to the diodes;
the discharge of the condensers is controlled sequentially by an electronic circuit controlled by software.